A phenomenological model for the aerodynamics of the knuckleball

摘要

The movement of a knuckleball depends on the seams of the baseball strongly, as a consequence a lift force proportional to the square of the ball velocity is occasioned. In this work we develop a model as a function of the position of the seams to compute the lift coefficient that appears in the lift force acting in upward direction, for four-seam (4S) and two-seam (2S) orientations of the ball. The result of the model is consistent with experimental data. In addition, deviations caused by lift force are calculated for all angles in the 4S and 2S orientations and some trajectories are generated.